Shaken by the loss of Russian natural gas since the invasion of Ukraine, European countries are questioning whether they can extend the lives of their ageing nuclear reactors to maintain the supply of affordable, carbon-free electricity — but national regulators, companies and governments disagree on how long the atomic plants can be safely kept running.

Europe avoided large-scale blackouts last winter despite losing its largest supplier of natural gas, but industry is still grappling with high electricity prices and concerns about supply.

Given warnings from the International Energy Agency that the coming winters will be particularly at risk from a global gas shortage, governments have turned their attention to another major energy source that would exacerbate the problem if it too is disrupted: Europe’s ageing fleet of nuclear power plants.

A tenth of Europe’s energy in play

Nuclear accounts for nearly 10% of energy consumed in the European Union, with transport, industry, heating and cooling traditionally relying on coal, oil and natural gas.

Historically nuclear has provided about a quarter of EU electricity and 15% of British power.

Taken together, the UK and EU have 109 nuclear reactors running, most of which were built in the 1970s and 1980s and were commissioned to last about 30 years.

That means 95 of those reactors — nearly 90% of the fleet — have passed or are nearing the end of their original lifespan, igniting debates over how long they can safely continue to be granted operating extensions.

Extension talk: Bridging the gap or a new lease of life?

Regulations differ across borders, but life extension discussions are usually a once-a-decade affair involving physical inspections, cost/benefit estimates for replacing major worn-out parts, legislative amendments, and approval from the national nuclear safety authority.

In some countries — especially for those that planned to exit atomic power entirely after the 2011 Fukushima nuclear disaster in Japan — discussion is focused on the short term: eking out a few years to get through any shortages before new wind, solar and gas installations can be built to take over.

Anti-nuclear Germany had planned to switch off its last three plants by the end of 2022, only to grant the sites an emergency extension to April 2023 to make it through winter without Russian gas — which previously made up 40% of EU gas supply.

In a 2022 poll from the Forsa Institute, just after Moscow’s invasion of Ukraine and the loss of Russian gas, 67% of Germans said the country’s nuclear shutdowns should be reconsidered.

This April, two thirds of Germans were still against the nuclear closures when they took place, with only 28% in support, Forsa found.

In gas-dependent Britain, two 40-year-old nuclear plants scheduled to close in 2024 also got approval this March to run through 2026, and potentially 2028, to help supplement power supply in the coming years.

In Spain, where seven reactors will start to be progressively shut in 2027 with a view to a full phaseout by 2035, the conservative opposition People's Party (PP) won the most votes in July elections on a platform that included reversing the Socialist government’s nuclear exit policy and instead extending Spanish plants’ lifespans.

“We cannot unplug 21% of the [electricity] installed in Spain without having another 21% capable of running with renewables … The price of energy would rise exponentially,” said PP leader Alberto Nunez Feijoo.

Belgium already performed a U-turn this January on its 2025 nuclear phaseout plan, after the war in Ukraine forced the government to rethink increased reliance on natural gas.

Its two youngest nuclear reactors received permission to run through 2036, adding an extra decade of life — but despite pleas from Belgian politicians, the country’s three oldest reactors are not being considered for a short-term renewal to cover expected power supply gaps over the next two winters.

“They're almost 50 years old, they're at the end of their life,” Catherine MacGregor, CEO of energy company Engie, which operates the Belgian fleet, told Reuters in June.

That view is far from universal.

So far, Finland, Sweden, Bulgaria, the Czech Republic, Slovenia, the Netherlands and Hungary have all taken steps to allow reactors to run for at least 60 years, subject to regular safety checks.

France, with the largest fleet, is carrying out a major 40-year inspection and refurbishment programme for its 32 oldest reactors.

ASN, the national safety authority, has said France’s pressurised water reactor (PWR) design in principle can be safely operated for 50 years — meaning the ageing plants can run through 2030 — but the regulator will not take a stance on extending to 60 years until the end of 2026.

“The burden of proof is on us,” said Etienne Dutheil, director of nuclear production at EDF, which owns and operates the French fleet, at an industry event on lifetime extensions earlier this year. “We are convinced of the ability of our components to continue operating over time … Reactors that are completely comparable to ours have 60-year operational licences in the United States.”

But a licence approval isn’t proof it can be done: The world’s oldest operating reactor, Switzerland’s Beznau 1, will only turn 54 this year.

Conviction and international comparisons also aren’t enough, Dutheil added, due to France’s particularly stringent regulatory requirements. “We have to [physically] demonstrate to our regulator that our equipment is able to keep functioning past 50 years, maybe even past 60 years.”

Some companies are pushing the limits further.

In February, Finland’s Fortum obtained permission to operate two reactors until 2050, when they will reach 70 years of age.

In Sweden, where licences are unlimited in time subject to regular safety checks, Vattenfall is considering 80 years of operation for its five reactors.

“We feel completely comfortable operating them further to 80 years — there is nothing that we have identified so far that isn’t doable” as far as upgrades are concerned, said Martin Darelius, Vattenfall’s senior advisor on nuclear technology.

More than scientific one-upmanship is at play.

Transitioning to cleaner, more efficient energy

Countries are under pressure to limit global warming by cutting their emissions of polluting greenhouse gas CO2 — that means cutting oil, coal, and eventually natural gas out of the energy mix.

And while scenarios for a climate-neutral 2050 call for a drop in overall energy consumption, power demand is set to grow as transportation and heating increasingly switch to electrification.

The European Union’s climate pledges would require power generation to increase by some 90% by 2050 to meet demand, according to the International Energy Agency.

Renewables are also intermittent, supplying power only when the sun shines or the wind blows, for example. That unpredictability can lead to wild swings in electricity prices, something governments are keen to avoid.

That has led experts to warn of a “cliff-edge effect” on power supply if current nuclear plants are turned off.

For many, investing to keep existing nuclear running as long as possible makes good business sense compared to the price shock of pulling the plug on a significant share of EU electricity that is nearly emissions-free.

This year, sixteen governments formed a European nuclear alliance aimed at maintaining the EU’s share of atomic power even as consumption grows, both via operating extensions and building 50 gigawatts (GW) of new reactors by 2050, up from 100 GW currently.

The alliance, which calls for nuclear to be counted alongside renewables in mandatory EU quotas for clean energy installation, faces opposition from a rival group.

Opponents include anti-nuclear countries like Austria and Germany, as well as countries who worry grouping nuclear with renewables will lead to less action to protect the climate.

That’s largely due to ideological objections to atomic energy, environmental worries over radioactive nuclear waste, and the concern that money to build new nuclear plants over decades could be better spent on quicker-to-install alternatives that can lower emissions well before 2050.

Many people also erroneously believe nuclear emits a high amount of planet-warming greenhouse gases.

The cost of pulling the plug

Politicians are also under pressure to keep energy prices low, especially as movements characterising climate action as costly and elitist gain ground.

That means ensuring steady, abundant supply — any swift, unexpected loss of a major source means market spikes and painful household bills.

Energy prices in Europe jumped exponentially in 2022 after many French reactors went offline. The impact was compounded by Russia’s invasion of Ukraine.

Approximately half the French nuclear fleet was down due to a combination of maintenance delays following COVID-19 lockdowns and a stress corrosion problem — which meant the safety piping on several reactors had become brittle and needed replacing, while others needed to be monitored in case they were at risk.

The issue affected EDF’s newer, more complex PWR models and not the standard-design reactors currently up for extension across Europe.

Problems increased in the summer when a heatwave lifted temperatures in rivers — the water is used to cool reactors — and reduced some to rocky beds. EDF issued production warnings and extended maintenance, while concerns grew in Germany over potential fuel shortages in the winter as rivers ran too low for barge traffic.

Forward prices surged as energy traders feared rolling blackouts and forced consumption cuts —then cashed in on the opportunity.

The worries of winter shortages did not materialise as temperatures remained mild and countries cut energy use.

But politicians are reluctant to repeat the exercise in years to come, as they tally up the damage to Europe’s industry — the steel, aluminium, chemicals and paper sectors are still dialling down production this year in response to high prices, prompting global competitiveness concerns.

“We have to ask ourselves if we are able to afford this combination of decarbonisation and increased electricity consumption, and if we are ready to balance it only with energy savings, energy efficiency and renewables,” Czech Industry Minister Jozef Síkela, who led EU country negotiations to pass a mandatory energy consumption cut, told Reuters.

“I’m pretty sure that’s a no — we need a stable, carbon-free source of energy, and the only one we know of for the time being is nuclear,” Síkela added.

What it will take: engineers, welders and billions, oh my!

Where building a new plant can take decades and cost around 14 billion euros, investing in a lifetime extension can be done for less than 1 billion euros and take place gradually, by replacing ageing components during regularly scheduled maintenance or refuelling periods every 18-24 months.

The biggest challenge is maintaining the reactor vessel, where uranium atoms are split to release neutrons inside the core. Those flying neutrons also hit the vessel’s steel walls, altering the lattice structure of the metal, making it hard and brittle.

Vattenfall and EDF try to slow down that embrittlement process by layering in special rods of hafnium metal or alloyed silver, which absorb the neutron radiation before the steel wall does — comparable to applying zinc to your nose at the beach to absorb UV rays before they reach the skin.

Other companies have experimented with an anti-ageing technique called annealing.

The idea is to heat up the metal to over 500 degrees Celsius for several days continuously then let it cool, causing the steel molecules to soften and “relax back” into their original, youthful configuration.

Reactor vessels are regularly inspected robotically, and contain a pocket of small steel samples that can be periodically extracted to determine how brittle the metal is getting over time.

Because those samples are closer to the core than the vessel wall, they age faster and act as an early-monitoring system — as a result, France’s Atomic Energy Commission (CEA) already has data on how brittle its vessels are expected to get at 60 years of operation, said Philippe Chapelot, CEA’s head of research on second- and third-generation reactors.

That allows the company to take special measures, such as lowering electricity output at some plants, to slow the ageing process.

Reactor vessels are generally seen as non-replaceable — though it has never been tried.

The same goes for the airtight containment building, which houses the reactor and all associated radiation-emitting parts, to keep it from being released into the atmosphere.

Otherwise, nearly all parts can be swapped out as needed.

In Sweden, the instrumentation and control (I&C) systems that allow workers to monitor all aspects of a plant’s health are for the most part still analogue.

“We are going to have to change the control systems to digital … that will be a sizable job,” said Vattenfall’s Darelius.

In France, workers in the plant control room still operate the site using relay — by flipping electric switches.

“It has the benefit of being extremely reliable, but you’ll admit it’s a little less fun than an iPhone,” said EDF’s Dutheil. “These technologies are no longer taught today in classes, and there’s the issue of being able to interest young people and getting them to acquire those technological skills that are a bit out of phase with the rest of their coursework.”

The French government, which this year nationalised EDF, has estimated it needs to hire and train at least 100,000 workers by 2033 if it hopes to run its fleet long term and build at least six new reactors.

That includes automation engineers, boilermakers, draughtsmen, electricians, maintenance technicians, blacksmiths, pipe fitters and welders.

​​Europe’s new pro-nuclear alliance would require some 450,000 skilled workers if it hopes to build an additional 50 GW of new nuclear by 2050, according to industry lobby Nucleareurope.

2050 and beyond: Hotter, drier, more radioactive trash

Industry cheerleaders point to Dubai’s new Barakah nuclear plant as proof reactors can be successfully designed to withstand desert heat and warmer water temperatures.

But few plants have room to be retrofitted with new safety systems, such as a dyke wall to protect against rising water levels, regulators warn.

“It’s a real headache to find [physical] space on a site that’s currently operating — we have reached certain limits in the feasible modifications of existing reactors,” said Karine Herviou, deputy director-general of France’s Institute for Radioprotection and Nuclear Safety, at the industry event on lifetime extensions.

The French fleet’s temperature margin to withstand heatwaves is constantly questioned, she added, while plant-specific climate simulations do not exist for lower river levels, increased wildfires, or extreme weather events like tornadoes and heavy wind and rain.

As a result, Herviou said in France: “There’s a general agreement that what we’ll do at the 50-year, 60-year mark will essentially be replacements for modernisation but very certainly not adding in any new safety systems … and checking for conformity and respect of already-applicable requirements, without further hiking the safety requirements.”

That rings alarm bells for third-party watchdogs like Mycle Schneider, who compiles the annual World Nuclear Industry Status Report and said ageing reactors need tighter scrutiny.

“You have a car, 30-to-40 years old, and your generator breaks down. You open the hood, the mechanic takes out the generator and then says, ‘Ooh, everything underneath is rotten’ — a 40-year-old nuclear plant is not all that different, you basically find on the go all kinds of things you didn’t expect to find,” Schneider said.

EDF wants the government to relax biodiversity rules which forbid plants from dumping used cooling water into nearby rivers on days they are deemed already too warm, limiting power production — which risks becoming more frequent.

Then there’s the issue of what to do with radioactive spent fuel.

Used uranium pellets, which are solid, are stored in special refrigerated swimming pools designed to cool the radioactive heat down for five-to-10 years. French company Orano then separates out the material into non-recyclable leftovers that are vitrified into glass (4% of the material), plutonium (1%) to create a new nuclear fuel called Mox, on which some 40% of France's reactors can run; and reprocessed uranium (95%) which for now can only be re-enriched and “recycled” at one plant in Russia.

Non-recyclable waste can be safely stored in dry casks, but its ultimate destination is deep underground, where it will fully degrade over hundreds of thousands of years.

Sweden, Finland and France have plans to build such long-term underground sites.

The safety question

For many, radioactive waste will never be safe, no matter how well-protected it is during transport and storage.

Attitudes on the safety of nuclear energy may be influenced by its association to nuclear bombs.

However, the concentration of uranium used for weapons is much higher than that used in nuclear fuel pellets, which may cause the reactor to melt due to overheating but not explode.

Statistically the fatality rate of nuclear energy is far below that of fossil fuels and biomass, even when including deaths from the 1986 Chernobyl and 2011 Fukushima nuclear accidents.

Vincent Zabielski, a nuclear engineer-turned-lawyer at Pillsbury Winthrop Shaw Pittman LLP in London, said it is a matter of perception.

“People worry about nuclear waste in a box, but you know where it’s not going? Into the environment,” he said, noting that air pollution from coal plants can cause acid rain. “The mercury in it winds up in your tuna salad,” he added.

Nuclear safety requirements have also continuously been beefed up by regulators to ensure past disasters are not repeated, complicating reactor design and making the initial commissioning and approval processes more stringent.

Even so, Europe’s newest plants have faced many issues in their construction, pushing off start times by a decade or more and causing budgets to balloon.

In Finland, Europe’s first new reactor in 16 years came online this April after an initial promise of a 3-billion-euro plant built in four years became 11 billion euros over 18 years.

However, it is expected to run for 60 years and supply 14% of Finnish power demand, more than covering the 10% of Russian electricity imports the country lost after the Ukraine war.

In Slovakia, new reactor Mochovce 3 is undergoing final testing with plans to enter commercial operation this autumn, a decade behind schedule and more than double its original budget. It will, however, eliminate dependence on electricity imports.

Britain’s under-construction Hinkley Point C reactor is also a decade overdue and billions over-budget so far, but the fixed electricity price contracted with the government is cheaper than UK power prices over 2022 when adjusted for inflation.

In France, announced plans to build new reactors by 2050 are met with scepticism given the numerous problems on EDF’s current fleet — not to mention the under-construction Flamanville 3 reactor, which was expected to come online in 2012 and has now been pushed to early 2024.

“The knowhow in terms of maintenance has been well-mastered. However it’s not the case with new construction,” former EDF CEO Henri Proglio testified to the national assembly during hearings on France’s loss of energy sovereignty late last year.

“There is a deficit of experience among subcontractors … we have lost executives and continue to lose them,” Proglio added, as a generation of engineers and managers retire or take more lucrative jobs elsewhere. “You must have that in mind when talking about a subject over the long term — the competence of tomorrow is built today.”

Correction: A previous version of this story incorrectly referred to some nuclear reactors as nuclear plants.